Procyon

Procyon is Alpha Canis Minoris, apparent magnitude 0.34, and at 11.5 light years one of the nearest of all bright stars. It is a white star just beginning to evolve off the main sequence, type F5, and like Sirius it has a white-dwarf companion, Procyon B, the burnt-out core of what was once the more massive star of the pair. The Greek name means before the dog, because Procyon rises shortly before Sirius, the Dog Star, announcing it. It forms the Winter Triangle with Sirius and Betelgeuse.

Procyon B, its white-dwarf companion, was suspected from irregularities in Procyon's motion decades before it was finally imaged directly in 1896, a faint point of light drowned in the primary's glare, making the pair one of the earliest confirmed astrometric binaries, systems whose companion is inferred from a wobble in position before it is ever actually seen. Procyon's designation as Alpha Canis Minoris is secure and uncontested, unlike several of the ambiguous Alpha assignments elsewhere in this catalogue, since it is by a wide margin the brighter of Canis Minor's only two easily visible stars. Direct imaging of Procyon B remains difficult even with modern instruments, since the faint white dwarf sits extremely close to its far brighter companion in apparent position.

Sources AstronomyAndrew Fraknoi, David Morrison, and Sidney C. Wolff (OpenStax) with Almagest (Mathematike Syntaxis)Claudius Ptolemy

Ptolemy gives Procyon the nature of Mercury with Mars, and the tradition reads it for quick wit and activity that brings sudden advancement and equally sudden loss, Robson supplying the elaboration, Ptolemy the core. Procyon is one of Agrippa's fifteen Behenian stars, the set singled out in Renaissance magic for talismans, where it is paired with agate and with the herbs buttercup and pennyroyal. That makes it one of the relatively few stars for which a specific stone-and-plant correspondence has a named early-modern source rather than a modern invention.

Procyon's Agrippa correspondences are given as the stone agate and the herbs buttercup and pennyroyal; being one of the fifteen Behenian stars placed Procyon, alongside Aldebaran, Regulus, Sirius and the rest of Agrippa's set, at the centre of Renaissance ceremonial magic in a way most of the stars catalogued in this whole set of tables, named only for position and lacking any documented magical use, never were. The pairing of quick wit with sudden reversal that Robson gives Procyon echoes the general Mercury-Mars formula applied elsewhere in this catalogue, intellect supplying the gift and the martial component supplying the instability that undoes it.